Range-finder.



PATENTED AUG. 27, 1907.

. B. A. FISKE. RANGE FINDER. nrmonxox' run an 22, me.

3 SHEETS-SHEET I.

Witnesses A Horneys.

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aw m 1 H s a u U m A 3 D E T N E A P M m n Y EULA K u 3N II? FF n Rflm u m P P A 0O V4 6 8 0 N Witnesses PATENTED AUG. 27, 190?.

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4r 4 7 42? A llorn eys B. A. PISKE.

RANGE FINDER.

APPLICATION mum nu 22,,1906.

Witnesses rays coming through that object glass have been thus .01'

6.15 which is anangle of somewhat less than 7 minutes. As raysof light coming through an object glass converge to foci along their original directions, it is clear that the angular displacement of the two images is equal to the angle between the objects whose images are formed on the focal plane, supposing the instrument to be prop erly adjusted before using. By this means the angle between two objects if it be quite small, can be meas ured by measuring the distance through which it is necessary to move one object glass, in order to aline the images of those two objects. If, for instance, in Fig. 8, the line a 4 5 3 b indicates a bundle of rays coming from distant object behind the observer, and the line c 2 3 b, parallel to a 4 5 3 6 indicates rays coming from a distant object in front of the observer, and if the prisms 4 and 3 be placed with their reflecting surfaces perpendicular to each other and the lenses 2 and 5 placed with their axes oi collimation along the lines a 4 5 3 b and c 2 3 b, and the lenses at the distances of their local length from the plane of the rear edge of the prism 3, then the images of the rear and front objects will be alined at b in the plane of the rear surface of the prism 3, where they can be viewed by the eye-piece. If now rays from another distant object comealong the line d2 3 e, those rays will form an image at e; and as the angle 6 2 b c 2 d, and as the angle e 2 b is the angle whose tangent displaced must be the angle whose tangent is it is plain that, ii we measure the distance .1! b and know the focal length e 2, we can find at once the angle 4: 2 d. It is also plain that the distance eb can be easily measured, if we move the lens 2 parallel to itself until the image it forms is moved from s to b, and we then measure the distance the lens 2 is moved, which dis tance is, of coursejequal to e b, the distance between the two images. It is also plain that ii the rays 0 2 and d2 come fromsay the bottom and top of a mast whose height h is known, then, letting D equal its distance from 2, a

D h==focal length :movement of lens,

D=hXfocal length 'of lens movement of lens.

As the focal length of the lens is lcnown, and as the movement of the lens can be measured, it is plain that, ii h'be known, thedistance D can be determined by the same operation as in using the stadimeter, and the micrometer graduated in units of distance. If we refer new to Figs. 1 and 7, it will become plain'that an observer at A can by this means measure the angle of depression, F1A E, if he can aline E with some image on the horizontal line A F; thereby revolving the line A E through the angle F A E; and also that he can determine the distance A E if he knows in addition the length oi the line A C. It is also plain that hecan ,accomplish the same result if-he alines E with some point on A D or A D, provided hedisplac es the image of E by an angular amount equal to the angle of A D below the line A F, or of A D" above the line A F. In other by, this instrument an observer can measure the co A E either from A or from E. The mechanto 14 inclusive. In Fig. 8, 1 represents the e'ye B means of which this is accomplished is shown in.

piece lens; 2 is one of the two object glasses, 8 is a prism,

'which covers one-half the field of the eye-piece in a is the other object glass, and it is arranged between the two prisms, and so placed that the rear of edge 0! prism -3 is in its focal plans. As shown'in 8, an image formed by the lens 2 will appear directly upon the focal plane, and be observed through the eye-piece lens; and at the same time rays of light from the rear will bereflected through the prisms 4 and 3, and an image will be formed by the object glass 5, which image will be on the same focal plane; each image will occupy onehalf the focal plane, and the observer will see both at the same time, the two images being separated by a vertical line, which is the reai vertical edge 'of prism 3. Means are provided for moving the object lens 2, so that the different angles a b (Fig. 8) may be measured.

In the preferred embodiment of the invention, the lenses and prisms illustrated in Fig. 8 are supported upon or within a central member, 10, and two tubes, 6 and 7. The central member 10 is provided with shorizontal pivot 8 so as to be movable in a vertical plane on the support 9, which in turn is capable of being swung horizontally on its vertical pivot which is fitted on a suitable standard or pillar of a height convenient to the operator. The instrument may therefore be turned to any angle of the azimuth or altitude. The tube 6 is secured to the central member by having a flange 11 formed upon it, which' flange is secured by screws 12 to the central member. This flange 11 carries upon it an arm 13, to which the prism 3 is rigidly secured. The arm 13 is provided with raised edges which form a retaining wall or support for the prism 3. By this means the prism is held in place, immovably in relation to the tube 6. The other end of the tube 6 serves as a support for the tube 14, which slides within it and carries the eye-piece lens 1. The tube 14 is slidable within the tube 6 in the usual manner, so that the observer may bring the image to the point of clearest definition.

Attached to the central member 10 by any suitable means, as by the screws 15, is a frame 16. This frame 16 extends below the tubes 6 and 7, and has a long longitudinal opening 40. It is provided with means for supporting and adjusting the position of the lens 2. The lens 2 is carried within a short length of tube 17 (see Fig. 12) which tube is mounted'in a frame 18 (see I Fig. 10 This name slides within Ways 19, in a frame 20. The ways 19 are vertical so that the frame 18 may move up and down in a vertical direction. This movement is obtained by means of a micrometer screw 21, which passes through a nut carried by theframe 20, its lower end engaging with the frame 18. The frame 18 is elevated and held inengagement with the screw by means of two springs 22, one on each side of the screw, The micrometer screw 21 is provided with an adjusting wheel 23, which is divided into divisions of angular measurements, I as will be explained. The frame 20 carries a supplemental frame 24, which extends over the top 01 the micrometer wheel.23, and carries a bearing 26 for the upper end of the screw. This frame 24- also carries an index finger as we 11 This finget is adapted toregister with the divisions of Blemicrometerwheelza.

The frame 20 is carried upon an arm 27, which is pivoted to the frame 16. The details of this pivot are best shown in Fig. 13. A support 28 is scoured by suitable l means, such as by screws, to the fitting 16. This support-has a. central opening through which the arm 27 passes. The arm 27 is provided with a pin 29 having pointed extremities which engage in hearings in the inner ends of the bolts 30, which are supported upon opposite sides of the arm by the support 28. Lock nuts 31 hold the bolts 80 in place. A strap 32 connects the open upper ends of the support 28, and upon being-removed, permits the more ready reaching of the pivot and removal of the arm 27 Near the opposite end of the arm 27 is a screw 33 having e rnilled head as shown. This screw engages upon the arm 34, which is horizontal. and pivoted at 35 to tho frame-16, As shown in Fig. 11, the pivot 35 is of considerable length and passes through a long bearing formed within a standard carried by or formed integral with the frame 16, so that the arm 34 will be rigidly supported. The arm 34 providedrwith a scale 86, similar to the stadimctcr, the scale indicating feet, which indicates the masthcight. The lower face of the arm 34 is, in engagement with a micrometer screw 37, which has a follower 38, which rests against the lower face of the arm 3G. The scrcw 37 is carried in a carriage 39, which rcsts within the central opening 40, in the frame 16. The carriage 39 is provided with a flange 41, which engages with thercar face oithe frame 16, so that the carriage 39 will be rigidlyheld in place. A central screw 42 passes through the cur riagd 39, and freely turns in the opening in the ll'fllllt' 16. The screw is provided with a wheel 43 and with a collar 44, so that it inay be rotatcd and slide the carriage 39 through the length of the opening 40. The rliicrometer screw 37 is provided with e 110941 45, which has lined divisions arranged upon a spirnl'line oi the shine pitch as the screw. A fixed finger 46 is carried by the carriage 39 so as to indicate the divisions upon the micrometer wheel. A spring 5Q is used to keep the screw 33 constantly in contact. with th'earm 34, and the arm 34 with the follower 38.

The prism 4 is carried upon it tube 47. 'lliistubc is carried on a tube 48 formed upon the central member 10-, and the tube 43 carries the object glassfi. The tube 48 is provided with a pin 49 over which rests a notch in' the lower end of the tube 48. A similar notch in formed upon the opposite side of the tube 47, so. that upon its being liitcd iron: the tube 40, it can he rotated a half revolution and again hold in place-by the engagement of the notch and pin. The periphery of the micrometer wheel 23 is divided into one hundred equdl'divisions.

Two scales are used, one reading from right to lcit and the other irorn leit to right. At the point marked 0 both scales are the some, Opposite 10 in one, the other shows 90; opposite 20 in one, the other nhowsSO, and so on. The upper'scelo indicates the omount by which the object glass 2 is depressed; the lUWl'I scnlc indicates v7 thenmount the object glass is raised, or vice vt-rsu. The acale'atl is divided into loci us is the similur'scalv outho stadimeter. This'rv ircscnts in tlululrizonn'u-r the height oi the operator, while in tin; studinn-h-r it represents the height of the target. 'llnnllcionuicr ,zjvheel-lfi'is'dlvided into yards, and indicates the disthe observer and the tor-get The focal d' ili'eioni t nn sz dad a no coincident, The

eye-piece lens being focused therefore upon this plane, the observer sees both direct and reflected images with equal definitenose (see Figs. 2, 3, 4, 5 and 6).

The operation of the device is as lhllows: In order to adjust the instrument, the follower 38 is first udjusted on the scale 36 of the arm 84, to the height of the observer This is accomplished by, turning tho head 43 and moving the carriagoSQ to tho desirodposition. The distnnco indicated we will first assume to be equal, to the line A A". The length of the line A C may be determined by the calculation to l)0 ln-rcinnfter explained. The prism 4 is then directed to thb front by turning the tubc 47 a hall revolution and sctl-lng the opposite notch in connection with the pin 49. Upon looking through the eye-piece and focusing it propcrly, the observer should one images similar to tins-c shown in Fig. 2, and in which ii the instrument is correctly adjusted, both direct and rcflcctccl horizons nppmu' exactly alinvd. In the apparatus shown in the druwihgs, the prism is upon thev rightsirlv of the instnnncnt as the observer uses 'itfliut owing to the inversion of the images by the eyepiece lows. the ilungc which is seen through the prism appcm-s upon the loft Side of the fluid of view and vice vernal. The horizons D D appear upon both sirlcs of tho vcrtical lino sop-muting lhc two images If the instnnnont he not adjusted, and ii there is any difference in ulincmerit lwtwccn tho two iinugcs oi the horizon, this (lilicrcnco can. lie corroctcd by moans of the screw 33, which will screw up or down the arm #3? and with it tho ulijvvt glass 2; so that both images oi the horizon may he ulincd. Tho operator then turns the lnlm 46 imlisvuy round so that the vertical sidc oitho prism 4 is to the Your. and is located as is shown in Fig. 9. The inulgvs shown in Fig. 3 will Thcnnppoun 'llnhorizon Dutthe front will up u-ur as below. lwlnw. the true horizontal F ll; and tho horizon l). lit-lug inverted. nmwurs nliovv tho llllt' horizontal 'llw oprmlnr will now adjust the adjusting win-cl 23 by turning it to ill! right. and lowering the uhjccl glas '2 until thrmum I) apparently rim-s ninl nliln-s' with the horizon D". 'llnimngcs will he similar to those shown in Fig. 4. it is iu-rrssm'y to luv/011 the object glass in order to got the apparent clcvntion oi the iinugc lly 'rcasmrni the inversion of imagcn by the oycqwiccc ions. 'llwnngnlar distance that the nlrjvt-t glas will lnwo hwniloprcesm'l, will licu monsuru of tho ungl'c DVA ll. us alrerulymxpluimd. Obviously the angle 1 A F or F A D is one-half of this unglo. (Hist-wing tinrv-ruling upon the uppcr side of the adjusting wlu'u-l '23. the operator now turns it hack inst one-hall of this Iizltllllg', for example, if the wheel 23 had lam-n tnruwl through divisions, he turns it bncklhirly (ll\l:-=lult.-. The images will then appear its in Fig. 5: and the horinon D will exactly coincide with tlw'h'mlnuiiunlul F ll; llltll is, in Figs'. 1 until the lllw U will have been rt-vnlvml through the laugh- FA l The inslrn nn-ul is now znljustml and rcndyiur uric. li'rnow tho 1 u'nglt l) A it is measured. and uddiu'l In the until I" A ll, which is rquul ill F ll tho tuhtl-unglc nI-dqn'r-ssion F A P will have lwen incur-lured. This is done hy slept-swing thee-him again. until tluiningo oi the water lino oi the target is ulinnd with tho inntge oi the roar horizon D, that; revolving thc lino A E through the angle F A E; This is shownin ru e, the

arrows on the left of the field of view indicdting the two horizontal lines which are to be brought into alinement. This alinemcnt is secured by means of the micrometer wheel 45, which through the agency of the arm 34, and arm 27 acting upon the principle of the stsdimeter, moves down the object glass 2; and the amount of movement necessary to produce the alinement is shown by the gradustions on the micrometer wheel 45 which are in units of distance. In case the front horizon cannot be seen in line with the target, the instrument is turned in some direction in which both front and rear horizons can be seen, and the image of the front horizon adiusted up to the horizontal in the way just described. The instrument is then turned towards the target, end the distance measured, as before, by turning the micrometer 45 until the image of the water line of the target is raised up to the reflected image of the rear horizon D.

In case the rear horizon cannot be seen opposite the direction of the target, the front and rear horizons are alinedin the way just described. The prism 4 is then reversed so that its vertical side is to the front, and the adjusting wheel 23 is turned in the reverse direction until it has raised the object glass 2 a dis tance equal to one half the distance it was-lowered,

.ilunges seen in Fig. (i would appear.

had been lowered by turning wheel 2?, 60 divisions, the observer would raise the glass 2 by turning wheel 23', 30 divisions in the opposite direction; and the In order thereafter to measure the angle F A E it is but necessary to bring the waiter line of the target into ulinement with the left hand image of the front horizon, as shown by the arrows in Fig. 6, thus, as before, measuring theangle EAD+DAF=FAE, the angle of depression of E.

A G, the height at which the studimeter is to be set, is found as follows. Clearly it is nearly equal to A A, the height of the observer above the water, but it is not difficult to [ind it quite accurately. By formulas 235 and 239 of Chauoencts Astronomy, Volumel,

a being the radius of the earth in statute miles.

By Chauvencts Astronomy, page 178, Volume 1,

A n= t/m thus depressing the right image of the front horizon KW below the left image of the front horizon by an angle equal to F A D. 'For example if the object glass 2 substitute in (4) 2AA 4 1 4 6272(AA) 2 15 MA A A i T FA"E=.92 l '-=l.98 6

. 16 (A /E) iv E) 92 6X AE AE But the tangent F'A E=(within allowable limits of error) A" o tan A E If the range A '1 were two miles, or 3,520 yards, the correction would be i er '98X1317,

so that if the height of the observer above the water were 75 feet, the liorizorneter should be set at 77.3 feet on the scale 86. v

In practice, I prefer toconstruet the apparatus as touches possible like the, stadimeter. In the stadimeter tho'scsle 86 has the 100 foot mark 4 inches from the pivot, 2 00foot-"mark '2 inches from the pivot, and

soon; ;The micrometer screw 37 is a. 24 pitch screw.

The screw 33 is as distant from the pivot 29,- as is the object 2, therefore any vertieslmovenrent of the screwmoves' the glass an equal distiinee. In one sctual instrument, the micrometer scrbw 21 is it 40 pitch screw, and focal length of the lenses 2 and 5 is 5.15 inches. The last graduation on the micrometer wheel 45 is 3200 yards. 1

By turning the micrometer wheel 45 throughone revolution thus indicating 3200 yards, its point will be advanced 1/24 of an inch, and the object gloss 2 will be lowered by an amount depending on the, position .of the screws 33 and 37. If they areopposite eiich other, the object glass 2 and its images on the focal plane willbe moved 1/24 inch. In order todetermine the correct position of the screw 33, which is permanent the following calculation is made:

that is, thescre'w 33 should be placed at the mark 77.7 feet on scale.

In place of the prisms 3 end 4 it is obvious other form of reflecting device, may; be employed.

One other form of device for thispuzpose will heme-,

rors similar to those used apps as;

sextant. If a mirror shouldib.sd'listitiitd 'fforthe Prism it could be-of theasriie smug, mgr-Prism lilo so as to reflect but one-half of'th' the eye-piece, or could extend across the entire fossil plane;

but with one-half of its suriace silvered and the other one-half unsilvercd.

In accordance with the provisions of the patent statutes, I have described the principle of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof; but I desire to have it understood that the apparatus shown is only illustrative, and that the invention can be carried out by other means. It is obvious, for instance, that the lens 5 could be moved instead oi the lens 2, in order to aline the images of the two horizons.

Having now described my invention, what I claim and desire to secure by Letters Patent, is:

1. In a range finder-,ihe combination with means for simultaneously observing direct and reflected images of the horizon of means (or displacing the image of the target through the angle 0! the dip, and means for mess uring the sngle'between the front or rear horizon and a previously displaced image of the target, thereby measuring the angle or depression of the water line of said target.

2. In a range finder, the combination with means for observing the horizon, by means or a reflected image, and means for observing the horizon by a direct image, means for observing both images simultaneously, the direct ob servation means including an object lens, andmeans for moving the lens to measure the angular distance between the direct and reflected images.

3.1 111 41 range finder, the combination with an eye-piece. and an object lens, of means for reflecting an image from r 5. In a range finder, 'the combination with an eye-piece,

or a reflecting means for observing an image in the trout or rear, an objective lens for taking a direct observation.

in tront and means for moving the objective lens perpendicular to its axis.

6. In It range finder, the combination of an eyepiece, a. reflecting means for observing an image at the front or rear, an objective lens for observing an image by direct observation at the, front, and means for moving the objective lens, such means comprising a pivoted lever engaging with the objective lens on one side of the pivot and engaging with a lever on the other side of the pivot, such lever being moved by a micrometer screw which is carried in an adjustable bearing.

7.'In a range finder, the combination of an eye-piece, a reflecting means, an object lens, apivoted lever, carryin the object lens on one side oi the pivot and engaging with a second lever on the other side of the pivot, n travellng carriage, a micrometer screw carried thereby, and means-for engaging the screw with the second lever.

8. In a range finder, the combination with an eye-'piece and an object lens, or a reflecting means, said reflecting means being adJustably mounted so that It may reflect in object from the front or back.

i). In a range finder, the combination 0! an eye-piece, a pivoted lever, an objectlxe lens mounted on one end of the pivoted lever and means including a micrometer screw engaging the otherend oi. the pivoted lever for" moving the I objective lens perpendicular to its axis.

10. in a range finder, the combination with a central member, of a prism within the central member, the said {HlSm occupying a portion of the width or. the focal plane, nn'eye-plece, a vertical extension on the central member carrying a second prism, an object glass, a lover carrying the object glass, means for adjusting theposltlon of the o ieet glass in relation to the lever, is second lover, a con nection between the two levers, a micrometer screw, the hearing for the screw being adjustable in relation to the second lever, and a connection between the screw and the second lever.

This specification signed and witnessed this 8th day or March, 1906.

BRADLEY A. FISKE.

Witnesses:

Lnossnn H. DYnn, Ann. Lone. 

